First you find a common denominator--in this case, it's 12. Then whatever number you multiply each individual denominator by, you also multiply it's numerator by. So now you have 4y/12 + 24y/12 - 6/12 = 12y/12 + 42/12, wherein the 12's all cancel out, giving you 4y + 24y - 6 = 12y + 42, or 28y - 6 = 12y + 42. Your next step is to divide both sides by 2, giving you 14y - 3 = 6y + 21. Add 3 to both sides and you have 14y = 6y + 24. Now subtract 6y from both sides and you get 8y = 24. Your final answer is that y = 3.